The present invention relates to a coffee or tea maker including an intermediate vessel for the brewing water. The intermediate vessel has an outlet siphon for periodic emptying, and is provided with a ventilation pipe, while otherwise being completely enclosed except for a water inlet.
German Offenlegungsschrift 36 43 878 (published unexamined application), a counterpart to U.S. Pat. No. 4,784,051, discloses a coffee or tea maker of this type.
The intermediate vessel, which can be periodically emptied by means of a siphon, serves to initially collect a predetermined quantity of heated brewing water and to convey the water relatively rapidly into the filter vessel positioned below the intermediate vessel.
The ventilation pipe serves to remove the air from the intermediate vessel, which is completely sealed except for the water inlet, and thus to allow it to be reliably emptied.
If during a final interval of the brewing stage the intermediate vessel is filled only partially with brewing water, the steam following the water nevertheless causes the intermediate vessel to be emptied. This emptying phenomenon arises, given that with the appropriate cross-sectional configuration of the ventilation pipe, the resulting pressure in the intermediate vessel ensures that the brewing water is able to flow over the overflow edge of the siphon even if the vessel is filled only partially.
Although the basic concept of such coffee or tea makers is certainly operational, difficulties arise in the accurate matching of all components of the intermediate vessel for maintaining the efficiency of the siphon under all operating conditions.